1. Field of the Invention
The present invention relates to technology for inspecting a printing image that is sequentially being processed by a plurality of processing steps.
2. Description of the Related Art
In line with the progress of computer technology, computer-based digitization has come into widespread use even in prepress systems for commercial printing. In a digital printing prepress system, print image data (for example, PDF data or PostScript data, PostScript being a trademark of Adobe Systems Incorporated) is received, various data processing is performed on this print image data, binary plate data is prepared, and either a plate or screen film is outputted using this plate data. Furthermore, recently binary print image data is being prepared in printing prepress systems, and on-demand printing, whereby this binary print image data is sent to an on-demand printer and direct printing is executed, is being carried out. In this specification, the overall process for preparing this kind of binary plate data and binary print image data is referred to as “printing prepress.”
In the printing prepress process, it is important that a printing image be revised in accordance with client instructions. Thus, special care is taken in carrying out the proofchecking of printed material, and in conducting plate image inspections for checking whether or not proofchecking results are being accurately reflected. In a digital printing prepress system, a plate image inspection is carried out by comparing binary plate data before and after proofchecking.
Recently, the importance of plate image inspection processing in particular is increasing. One reason for this is the desire to reduce the number of times that proofs are outputted in order to reduce printing prepress work volume and costs. For example, when a slight change is added immediately prior to final output (the output of a plate or printed material), since it is not necessary to confirm the contents of the revision with the client, who is the originator of the printing order, the proof is most often omitted. Another reason is because, for example, since a printing image is processed as digital data, and an operator can easily change the print image data, there is the risk of errors occurring as a result of this. Thus, when a relatively insignificant revision is added, failure to check this revision properly runs the risk of the final printed material being no good. Thus, the desire to carry out plate image inspection processing automatically for printed images between different steps has increased.
Also, in conventional plate image inspection processing, since plate data was compared before and after proofchecking, it was impossible to carry out a plate image inspection at the processing stage for outputting a first proof. Accordingly, technology for enabling a plate image inspection to be carried out even at the processing stage for outputting a first proof has been needed for some time now.